The present invention relates to a cleaner for a printed circuit board, or similar planar object.
In the manufacture of printed circuit boards, it is important that the board be clean before photo-sensitive film is laminated to it, or photo-resist screening is laminated to it. These printed circuit boards, at this stage of their production, have conductive patterns on them of very high line and space definition, meaning that the lines are quite thin, with very small spaces between the lines. Any extraneous material, known in the industry as "trash" is apt to interfere with the circuitry, such as by connecting a pair of conductors where no such connection is desirable. When this occurs, the printed circuit board is unacceptable, and must be rejected. Heretofore, there has been a relatively high rejection rate, despite the utilization of relatively intensive labor input in order to provide the boards free of "trash".
Apparatus has previously been suggested for the cleaning of printed circuit boards. Maca U.S. Pat. No. 3,636,662 and Call U.S. Pat. No. 3,691,582 are examples of machines for cleaning printed circuit boards, which include brushing the boards and applying liquid cleaning material to them.
Murray, et al U.S. Pat. No. 3,117,333 discloses an apparatus for cleaning aperture cards which includes a pair of rotating brushes and electro-static eliminators. These are provided in a first compartment of the machine, and adjacent to that compartment is a second compartment which houses a motor for driving feed rollers and rotating cleaning brushes, and also contains a motor-driven fan. Air enters the cleaning compartment through an upper opening, and passes through a removable filter, and thence through the cleaning compartment, passing through a second removable filter at a lower part of the cleaning compartment, and from thence travels laterally across the bottom of the cleaning compartment, where it passes through an opening in a wall of the cleaning compartment, and into the suction chamber of the motor-driven fan. The apparatus is bulky and the air does not sweep across the objects being cleaned, from the ends, towards the center.
Herbert, Jr. U.S. Pat. No. 3,395,042 discloses a paper-cleaning apparatus which is positioned above a moving web of paper, and which includes a suction nozzle having attached to it an ion emitter, follwed, in the direction of paper movement, by a first brush, an entry for air to be drawn into the nozzle and thence to a blower, and then a second brush, the air being drawn through the two sets of brushes.
Other machines for cleaning webs through use of brushes and ion emitting devices are shown in Sroka U.S. Pat. No. 3,915,737, Landry, et al U.S. Pat. No. 2,920,987 and Schwartz, et al U.S. Pat. No. 2,980,933. Further, Koppehele U.S. Pat. No. 3,189,929 discloses a machine for wiping a traveling film which includes a pair of box-like chambers having spaced, opposed walls providing a slot between them, terry cloth wiping elements mounted on the walls, and suction elements connected to each of the chambers. Durst U.S. Pat. No. 3,643,277 shows a machine for cleaning slats of venetian blinds, utilizing feed rollers, brushes of a rotating character, and a sprayer for liquid material.